The Maltese authorities have dropped all charges against British diver Stephen Martin, who was wanted for manslaughter in connection with a 2014 diving accident.

In a Facebook post, the British Sub-Aqua Club said: “This morning lawyers for BSAC member Stephen Martin were advised that all charges have been dropped by the Maltese Authorities, following a visit to the Island’s Attorney General by the British Sub-Aqua Club, last week.

It brings to an end a horrific nightmare for Stephen who could have faced up to ten years in prison if he had been found guilty in Malta.

Stephen was charged last July with two counts of involuntary homicide, following the deaths in Gozo in June 2014 of Larissa Hooley and Nigel Haines, despite the fact a UK inquest had concluded in February 2015 that they died due to a diving accident.

Speaking of his relief today Stephen said: “I am overwhelmed. This has been an utter nightmare for me, and I am just so relieved it is over. I feel I can finally start grieving for Larissa and Nigel, I just can’t keep back the tears.

“I would like to thank everyone who has supported me over the last 12 months – I have been overwhelmed by the support of divers in the UK and worldwide and for all the efforts that have been made on my behalf to get these charges overturned.

“BSAC have also been really been fantastic. It’s a great example of how they look after their members, and I can’t thank them enough.”

BSAC chief executive Mary Tetley said: “First of all I would like to extend our sympathies from all at the British Sub-Aqua Club to the families of Larissa Hooley and Nigel Haines. This was a tragic accident and Stephen is among the many who are still grieving their loss.

I would like to thank the Malta Tourism Authority for facilitating the crucial meeting with the Attorney General. The decision today brings to an end the horrendous ordeal which Stephen has suffered since he was charged, and we are both delighted and relieved for him.”

Stephen’s solicitor in the UK, Edward Elwyn Jones of Hodge Jones and Allen Solicitors described the charge as “bizarre” because it was not at all clear how the Maltese authorities proposed to prove that Stephen had actually caused the deaths of Larissa and Nigel.

He said: “We received notification from the UK Crown Prosecution Service this morning that the European Arrest Warrant for Stephen Martin had been withdrawn

“I have also received notification from the Attorney General in Malta that the intended prosecution will no longer be proceeded with. This brings to an end a long and painful nightmare for Stephen.

“It is rare for an extradition request to be withdrawn. Often when they are it is as a result of lobbying outside the courtroom and BSAC are to be commended for the work they have done to highlight Stephen’s plight at the highest level.”

Stephen’s MP Sir Peter Bottomley who has also been supporting his case, said:

“I’m grateful to the Maltese Attorney General for meeting with BSAC and reviewing the case and to Stephen’s lawyer Ed Jones.

“I also pay tribute to the British Sub-Aqua club and Stephen’s lawyer Ed Jones for their efforts in this case.”

Mr Martin was due to go to the high court in London on Wednesday to appeal against a European extradition warrant ordering his removal to face trial.

Maltese prosecutors were seeking to hold Martin, an IT manager from London, responsible for the deaths of Larissa Hooley, 48, and Nigel Haines, 59, because he was the diver with the most experience on the expedition in question. The accident had taken place in the area known as the Blue Hole near Dwejra.

They were swimming along a submerged cliff 10 to 15 metres below the surface when, 20 minutes into the dive, Hooley veered off and began descending rapidly, leaving a jagged lines of bubbles. Her friends followed, flashing torches in an attempt to elicit a response. She did not reply. By the time they reached her, Hooley had sunk to a depth of 35 metres. Coster and Haines brought her up in a 90-second ascent.

When Hooley surfaced her respirator was out of her mouth, she had turned a bluish colour and was unresponsive. Martin pulled her up on to land with difficulty; the water had become choppy. Mouth-to-mouth resuscitation failed.

Amid frantic attempts to save Hooley, Haines slipped back into the water. Crantson called a passing boat to help find Haines. His lungs had been damaged on the way up with Hooley, and he also died.

Martin cooperated with Maltese officials’ inquiries and then left the island. An inquest into the two deaths at Brighton and Hove coroner’s court in February last year returned verdicts of accidental death.

Maltese officials held a separate magisterial inquiry into the deaths in autumn 2014. Martin was not informed about or asked to participate in it. That inquiry found that he had been negligent because of the “unorthodox dive profile”, had not checked the weather conditions and that he had failed to keep a close watch on Hooley. Martin denies all the allegations. There is no suggestion of any intent to cause either of the deaths.

The Maltese inquiry did not have the benefit of hearing from Dr Peter Wilmshurt, a medical expert in scuba diving cases, who gave evidence to the British inquest into the two deaths and concluded they were accidental.

Both Hooley and Haines were found to have died from immersion pulmonary oedema, a leakage of fluid from the bloodstream into the lungs which prevents oxygen from being absorbed. The condition is not fully understood.

In July 2015, Martin was arrested at his home in Littlehampton, West Sussex, by police acting on a European arrest warrant stating that he had been charged with involuntary homicide.

He was held overnight and taken to Westminster magistrates court the following day. “The fact that I had been charged came as a complete surprise to me,” Martin said. “I didn’t agree to being extradited.”

Recalling the moment his girlfriend began to sink, Martin said: “We thought perhaps [Larissa] had dropped something and gone to recover it. She was probably dead before we reached her. [This extradition] is absolutely bizarre and has put me through hell for the last seven months.

“The ascent wasn’t that fast … but we couldn’t hang around. These things have to be treated on the surface. You only have seconds to get someone out of the water.

“We had checked the weather. We had been to another site and didn’t dive there [because of what we were told]. So we went to Gozo and the people said conditions were perfect.”